Ignition distributor



E. C. BETTONI July 10, 1962 IGNITION DISTRIBUTOR 2 Sheets-Sheet 1 Filed May I5, 1961 mmvm T N m M M M 2 0 I 2 M N IN m Hm win I w W I 1 H n vI}! m L W \\||.i||l|1|||l/./ 8 3 7 fillflf fllflf/lrl.hi% 2 D a 2 7 w M H A ZTOE/VE) July 10, 1962 E. c. BETTONI IGNITION DISTRIBUTOR 2 Sheets-Sheet 2 Filed May 3, 1961 INVENTOR. fZ/Gf/W? C bI rro/v/ United States 3,043,285 IGNITION DISTRIBUTOR Eugene C. Bettoni, Birmingham, Mich, assignor to Holley Carburetor Company, Warren, Mich a corporation of Michigan 7 Filed May 3, 1961, Ser. No. 107,423 6 Claims. (Cl. 123117) This invention relates to ignition distributors for internal combustion engines, and more particularly to pressure type distributors which use a double-diaphragm mecha nism, including a second surage diaphragm, for advancing the ignition spark.

In past ignition systems which utilized a double diaphragm mechanism to advance the spark, one diaphragm was actuatedby carburetor venturi and/or engine manifold vacuum and a second diaphragm was actuated by engine manifold vacuum. This second diaphragm was commonly called a surge diaphragm because the main.

function thereof Was to enable the first diaphragm to reposition the spark advancing mechanism when the throttle suddenly surged open. While this system worked well, if the surge diaphragm became ruptured, the entire advancing mechanism failed, and the engine would not function properly or not at all.

Accordingly, it is an object of this invention to provide a safety device for distributors or" this type which will enable a vehicle to be driven, even though the surge diaphragm may be ruptured.

It is a further object of this present invention to provide a safety valve for sealing off the main diaphragm chamber, not only when the throttle is opened suddenly but also in the event the surge diaphragm is ruptured. Since the surge diaphragm is a secondary feature to facilitate peak performance, the remaining portion of the advancing mechanism will operate at some condition less than top performance, but well enough to at least operate the engine until proper repairs can be made.

The advantages of this invention can be readily appreciated if one considers the inconvenience caused by the prior construction without the proposed safety valve when an ignition distributor failure occurs where no service facilities are available.

Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is an elevational View, with portions thereof in partial cross section taken along the line 1-1 of FIG- URE 2 and looking in the direction of the arrows, illustrating a distributor embodying the invention;

FIGURE 2 is a top plan view of the distributor shown by FIGURE 1;

FIGURE 3 is a view similar to the upper left hand portion of FIGURE 1, but illustrating a prior art construction.

As described in general terms above and as shown on FIGURE 1, distributor assembly has associated there with a double diaphragm assembly 12 connected to a carburetor assembly 14 mounted on an engine manifold 16.

Distributor assembly 10 includes a housing 18, a movable breaker plate 20, a shaft 22 positioned vertically and rotatable in housing 18, a gear 24 secured to shaft 22 and driven in the usual manner from the engine of which only manifold 16 is shown. Condenser 28, contact assembly 30, and cam 32 are positioned on the movable plate 20'.

The double diaphragm assembly 12 may be secured to distributor assembly 10 by screws 34 (better seen inFIG- URE 2). A link 36 connects in the well known manner between movable plate 20' and the vacuum diaphragm 38, and cotter pin 40 holds link 36 in position with movable plate 20'. The vacuum diaphragm 42 is positioned in housing 44, and diaphragm 38 is positioned in housing 46 of assembly 12. Thus, the diaphragm 38 forms chambers 48 and 50, and the surge diaphragm 42 forms chambers 52 and 54.

Housings 44 and 46 are fixed together so that they are air tight and form a common wall 56 which has a passage 58 connecting chambers 50 and 54. A spring 60 is compressed inside cylinder 62 by diaphragm 42, which has fixed thereto a valve member 64 adapted to seal off passage 58 and chamber 50 from chamber 54 when vacuum in manifold 16 is not sufficient to overcome the force of spring 66. A screw cap 66 seals the cylinder 62 and also seats spring 6t). A boss or other portion 68 may be fixed to cylinder 62 and formed with a passage 70- communicating with chamber 52, and a conduit 72 connects between the manifold vacuum orifice 74 and the passage 70. Chamber 52 and diaphragm 42 are thus continuously subjected to manifold vacuum at 16.

Chamber St is subjected to venturi and/or manifold vacuum existing at orifices 76 and 77 by means of con-- necting passages 78 and 79 having restrictions 80 and 81 therein, respectively. Conduit 83 connects passages 78 and 79 to chamber 50.

The structure described above is designed to be employed with a conventional carburetor assembly 14 comprising an induction passage 84 having a venturi 85 in which a fuel nozzle 86 is located, the carburetor 14 being mounted on the engine manifold 16 and having the usual throttle plate 88 disposed between the nozzle 86 and manifold 16.

Operation The general operation of a pressure type distributor such as that disclosed herein is well understood by those skilled in the art. The sparking in the engine cylinders is, of course, caused by the cam 32 opening and closing the ignition contact assembly 30 secured to the breaker plate 20 which is mounted for rotation about the cam. The springs 21 and 23 normally hold the plate 20 and contact assembly 39 in the full retarded position shown. However, as is well understood by those skilled in the art, certain engine operating conditions, the most important of which are engine speed and load, require that the ignition timing be at times advanced in varying degrees. Advance of the ignition timing in a pressure distributor is accomplished by rotation of the plate 20 in the clockwise direction in FIGURE 2 against the force of the calibrated springs 21 and 23. Rotation of the plate 20 is caused by the rod 36 which is secured to the main diaphragm 38, it being apparent that diaphragm 38 is moved to the left in varying degree during engine operation in response to venturi vacuum which is primarily an indication of engine speed and/ or manifold vacuum which is primarily an indication of engine load. These vacuums are, of course, sensed at the orifices 76 and 77, the latter being subjected to manifold vacuum when the throttle plate 88 is partially open.

The operation of a pressure distributor having only the diaphragm 38 is generally similar to the operation of the distributor shown by Mallory 2,268,490. However, as engines increased in size, the carburetor bores had to be increased in size and number. This reduced the vacuum that was available to provide ignition advance, and it was found necessary to increase the area of the main diaphragm 38 in order to maintain the same force available to advance the spark.

While increasing the size of the diaphragm 38 did provide the force required, it created another problem. If a vehicle is cruising at road load and it is desired to accelerate, such as when passing another vehicle, the throttle 18 is opened suddenly so as to immediately drop the manifold vacuum. Unless the ignition timing is simultaneously retarded temporarily, a so-called tip-in detonation or knock occurs. It was found, however, that the necessary restriction 81 maintained a sufficient vacuum acting on the larger diaphragm so as to prevent such a retarding of the ignition.

It was for this reason that the second diaphragm was added. The force of spring 613 was such that all manifold vacuums greater than a predetermined value would hold the diaphragm 42 to the left so that chambers 54 and 50 were in communication and, in effect, con stituted a single volume that had to be sufficiently evacuated by venturi and/ or manifold vacuum to move the main diaphragm 38 to the left and provide an ignition advance. However, when the manifold vacuum was reduced below the above-mentioned predetermined value, such as would occur on the acceleration referred to above, the spring 6t) would immediately force diaphragm 4-3 to the right and force any air in chamber 54 through pas- I sage 58 and into chamber 56. In other words, the volume of the vacuum chamber of which diaphragm 33 formed one wall was reduced; this, of course, increased the pres sure (reduced the vacuum) acting on the diaphragm and caused it to move intantaneouly to the right, giving an immediate retard of the ignition and elimination of the detonation.

The above described two-diaphragm construction (see FIGURE 3) satisfactorily eliminated the objectionable detonation on sudden throttle openings. However, since no means was provided to seal off chambers 54- and 5-9, a rupture or other failure of the diaphragm 42 would perrnit air from the manifold 16 to leak into and deplete the vacuum in the chamber 50, so it was impossible for the main diaphragm 38 to advance the spark.

In order to eliminate the above problem, the invention contemplates means to close passage 58 in the event of failure of the surge diaphragm. Thus, if the diaphragm 42 in the FIGURE 1 construction should fail, then the higher manifold vacuums required to move the diaphragm 42 to the left against the force of spring 6t? cannot be maintained in chamber 52 and spring 60 will move the valve member 64 secured to the diaphragm 42 to the right so as to seal off the opening 53 and prevent communication between chambers 54 and 50. While the benefit of the surge diaphragm will be lost, the usual ignition advance and retard in response to engine speed and load will still be maintained.

While only one embodiment of the invention has been disclosed for purposes of illustration, it is apparent that modifications thereof are possible Within the scope of the appended claims.

What I claim as my invention is:

1. In an internal combustion engine, the combination of an ignition timer, a fuel mixture intake passage-way including a venturi, a throttle valve positioned in said passage-way on the engine intake manifold side of said venturi, a first suction controlled means for varying the position of said timer, a passage connecting said first suction controlled means with said venturi and with said intake passage-way on the venturi side of said throttle valve when closed, a second suction controlled means secured to said first suction controlled means in a manner so as to provide a common separating wall, an opening in said common wall providing communication between adjacently disposed chambers in said first and second suction controlled means, said adjacent chambers forming in effect a single chamber to be evacuated in order to vary the position of said timer, a conduit connecting said second suction control means to said engine intake manifold, said second suction control means having a valve adapted to at times close said opening in said common wall.

2. In an internal combustion engine, the combination of an igniter timer, a fuel mixture intake passage-way including a venturi, a throttle valve positioned in said passage-way on the engine intake manifold side of said venturi, a first suction controlled means for varying the position of said timer, a passage connecting said first suction controlled means with said venturi, a second suction controlled means secured to said first suction controlled means in a manner so as to provide a common separating wall, an opening in said common wall providing communication between adjacently disposed chambers in said first and second suction controlled means, said adjacent chambers forming in effect a single chamber to be evacuated in order to vary the position of said timer, a conduit connecting said second suction control means to said engine intake manifold, said second suction control means having a valve adapted to at times close said opening in said common wall.

3. In an internal combustion engine, the combination of an engine timer, a fuel mixture passage-way including a venturi, a throttle valve positioned in said passage-way on the engine intake manifold side of said venturi, a first suction controlled means for varying the position of said timer, said first means comprising a housing with a diaphragm secured therein so as to form a first vacuum chamber, a conduit connecting said vacuum chamber with said venturi, a second suction controlled means, said second suction controlled means comprising a housing having a diaphragm secured therein so as to provide second and third chambers, said first and second vacuum controlled means being arranged so as to have a common separating wall and so that said first vacuum chamber is disposed adjacent said second chamber, an opening in said common wall, said third chamber being connected to said engine inlet manifold, resilient means urging said diaphragm in said second vacuum controlled means towards said common wall, and a valve member secured to said last mentioned diaphragm for at times closing said opening in said common wall.

4. A pressure type ignition distributor for an internal combustion engine, comprising a housing, an engine driven shaft journaled in said housing, a cam secured to one end of said shaft, a circuit breaker opened and closed by said cam on rotation of said shaft, said circuit breaker being secured to a breaker plate mounted for angular displacement with respect to said shaft so as to vary the relation between said cam and said circuit breaker, spring means urging said breaker plate in one direction, a first vacuum responsive means including a first vacuum chamber formed on one side by a first flexible diaphragm connected to said breaker plate for moving said plate against the force of said spring means, and a second vacuum responsive means including a second vacuum chamber communicating with said first vacuum chamber and formed on one side by a second flexible diaphragm, said first and second chambers constituting in effect a single chamber to be evacuated to effect a rotation of said breaker plate against the force of said spring means, said second diaphragm being spring biased in a direction to reduce the volume of said second vacuum chamber and said latter diaphragm having valve means associated therewith for at times preventing communication between said first and second vacuum chambers.

5. A pressure type ignition distributor for an internal combustion engine, comprising a housing, an engine driven shaft journaled in said housing, a cam secured to one end of said shaft, a circuit breaker opened and closed by said cam on rotation of said shaft, said circuit breaker being secured to a breaker plate mounted for angular displacement with respect to said shaft so as to vary the relation between said cam and said circuit breaker, spring means urging said breaker plate in one direction, a first vacuum responsive means including a first vacuum chamber formed on one side by a first movable wall connected to said breaker plate for moving said plate against the force of said spring means, and a second vacuum responsive means including a second vacuum chamber communicating with said first vacuum chamber and formed on one side by a second movable wall, said first and second chambers constituting in efiect a single chamber to be. evacuated to effect a rotation of said breaker plate against the force of said spring means, said second movable wall being spring biased in a direction to reduce the volume of said second vacuum chamber and said latter movable wall having valve means assocaited therewith for at times preventing communication between said first and second vacuum chambers.

6. A spark distributor, comprising an angularly adjustable plate for advancing or retarding the spark, a 10 2827889 5 passage through said wall.

References Cited in the file of this patent UNITED STATES PATENTS Smitley Mar. 25, 1958 

